(1) Field of the Invention
The invention relates to a drill comprising straight flutes. Drills comprising straight flutes are especially suitable for cutting short-chipping materials. In these drills, the flutes serve to remove the chips.
(2) Description of the Prior Art
In the case of innately long-chipping materials, however, there is the problem that the long chips jam over the course of the straight flute between the outlet of the flute and the adjoining secondary cutting edge. However, such jamming cannot be observed in the case of short-chipping materials. In cutting technology, therefore, it has been conventional practice for a long time to use drills having helical flutes. In this case, the helix configuration of the flutes has the function of diverting, as it were, the flow direction of the chips in order to break the chips inside the flute. As a result of this chip breaker function of the helical flutes, short chips are also produced in the case of long-chipping materials, which short chips can be removed by the helical flute without jamming between flute and secondary cutting edge.
A disadvantage in the case of the tools having a helical flute is the reduced bending resistance of the drill.
In the straight fluted drills according to the prior art, the main cutting edge has just as straight a course as the flute. As a result of the identical course of the main cutting edge and flute, said main cutting edge and flute can be ground in the tool in one operation by means of a grinding wheel.
Finally, it is known in the field of drills having a helical flute to give the main cutting edge an in particular nonlinear shape in order to influence the cutting behavior, for example the cutting edge sharpness or the stability of the cutting edge.
Proceeding from the prior art described at the beginning, the object of the invention is to provide a drill which is resistant to bending and which at the same time has a chip-breaking action and is especially suitable for cutting innately long-chipping material using short chips.